4 * Copyright (C) 1994 Linus Torvalds
6 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
7 * stack - Manfred Spraul <manfreds@colorfullife.com>
9 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle
10 * them correctly. Now the emulation will be in a
11 * consistent state after stackfaults - Kasper Dupont
12 * <kasperd@daimi.au.dk>
14 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
15 * <kasperd@daimi.au.dk>
17 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
18 * caused by Kasper Dupont's changes - Stas Sergeev
20 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
21 * Kasper Dupont <kasperd@daimi.au.dk>
23 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
24 * Kasper Dupont <kasperd@daimi.au.dk>
26 * 9 apr 2002 - Changed stack access macros to jump to a label
27 * instead of returning to userspace. This simplifies
28 * do_int, and is needed by handle_vm6_fault. Kasper
29 * Dupont <kasperd@daimi.au.dk>
33 #include <linux/config.h>
34 #include <linux/errno.h>
35 #include <linux/interrupt.h>
36 #include <linux/sched.h>
37 #include <linux/kernel.h>
38 #include <linux/signal.h>
39 #include <linux/string.h>
41 #include <linux/smp.h>
42 #include <linux/smp_lock.h>
43 #include <linux/highmem.h>
44 #include <linux/ptrace.h>
46 #include <asm/uaccess.h>
48 #include <asm/tlbflush.h>
54 * Interrupt handling is not guaranteed:
55 * - a real x86 will disable all interrupts for one instruction
56 * after a "mov ss,xx" to make stack handling atomic even without
57 * the 'lss' instruction. We can't guarantee this in v86 mode,
58 * as the next instruction might result in a page fault or similar.
59 * - a real x86 will have interrupts disabled for one instruction
60 * past the 'sti' that enables them. We don't bother with all the
63 * Let's hope these problems do not actually matter for anything.
67 #define KVM86 ((struct kernel_vm86_struct *)regs)
68 #define VMPI KVM86->vm86plus
72 * 8- and 16-bit register defines..
74 #define AL(regs) (((unsigned char *)&((regs)->eax))[0])
75 #define AH(regs) (((unsigned char *)&((regs)->eax))[1])
76 #define IP(regs) (*(unsigned short *)&((regs)->eip))
77 #define SP(regs) (*(unsigned short *)&((regs)->esp))
80 * virtual flags (16 and 32-bit versions)
82 #define VFLAGS (*(unsigned short *)&(current->thread.v86flags))
83 #define VEFLAGS (current->thread.v86flags)
85 #define set_flags(X,new,mask) \
86 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
88 #define SAFE_MASK (0xDD5)
89 #define RETURN_MASK (0xDFF)
91 #define VM86_REGS_PART2 orig_eax
92 #define VM86_REGS_SIZE1 \
93 ( (unsigned)( & (((struct kernel_vm86_regs *)0)->VM86_REGS_PART2) ) )
94 #define VM86_REGS_SIZE2 (sizeof(struct kernel_vm86_regs) - VM86_REGS_SIZE1)
96 struct pt_regs * FASTCALL(save_v86_state(struct kernel_vm86_regs * regs));
97 struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs)
99 struct tss_struct *tss;
104 * This gets called from entry.S with interrupts disabled, but
105 * from process context. Enable interrupts here, before trying
106 * to access user space.
110 if (!current->thread.vm86_info) {
111 printk("no vm86_info: BAD\n");
114 set_flags(regs->eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);
115 tmp = copy_to_user(¤t->thread.vm86_info->regs,regs, VM86_REGS_SIZE1);
116 tmp += copy_to_user(¤t->thread.vm86_info->regs.VM86_REGS_PART2,
117 ®s->VM86_REGS_PART2, VM86_REGS_SIZE2);
118 tmp += put_user(current->thread.screen_bitmap,¤t->thread.vm86_info->screen_bitmap);
120 printk("vm86: could not access userspace vm86_info\n");
124 tss = init_tss + get_cpu();
125 current->thread.esp0 = current->thread.saved_esp0;
126 current->thread.sysenter_cs = __KERNEL_CS;
127 load_virtual_esp0(tss, current);
128 current->thread.saved_esp0 = 0;
131 loadsegment(fs, current->thread.saved_fs);
132 loadsegment(gs, current->thread.saved_gs);
137 static void mark_screen_rdonly(struct task_struct * tsk)
145 spin_lock(&tsk->mm->page_table_lock);
146 pgd = pgd_offset(tsk->mm, 0xA0000);
154 pmd = pmd_offset(pgd, 0xA0000);
162 pte = mapped = pte_offset_map(pmd, 0xA0000);
163 for (i = 0; i < 32; i++) {
164 if (pte_present(*pte))
165 set_pte(pte, pte_wrprotect(*pte));
170 spin_unlock(&tsk->mm->page_table_lock);
177 static int do_vm86_irq_handling(int subfunction, int irqnumber);
178 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
180 asmlinkage int sys_vm86old(struct pt_regs regs)
182 struct vm86_struct __user *v86 = (struct vm86_struct __user *)regs.ebx;
183 struct kernel_vm86_struct info; /* declare this _on top_,
184 * this avoids wasting of stack space.
185 * This remains on the stack until we
186 * return to 32 bit user space.
188 struct task_struct *tsk;
189 int tmp, ret = -EPERM;
192 if (tsk->thread.saved_esp0)
194 tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
195 tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
196 (long)&info.vm86plus - (long)&info.regs.VM86_REGS_PART2);
200 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
202 tsk->thread.vm86_info = v86;
203 do_sys_vm86(&info, tsk);
204 ret = 0; /* we never return here */
210 asmlinkage int sys_vm86(struct pt_regs regs)
212 struct kernel_vm86_struct info; /* declare this _on top_,
213 * this avoids wasting of stack space.
214 * This remains on the stack until we
215 * return to 32 bit user space.
217 struct task_struct *tsk;
219 struct vm86plus_struct __user *v86;
223 case VM86_REQUEST_IRQ:
225 case VM86_GET_IRQ_BITS:
226 case VM86_GET_AND_RESET_IRQ:
227 ret = do_vm86_irq_handling(regs.ebx, (int)regs.ecx);
229 case VM86_PLUS_INSTALL_CHECK:
230 /* NOTE: on old vm86 stuff this will return the error
231 from verify_area(), because the subfunction is
232 interpreted as (invalid) address to vm86_struct.
233 So the installation check works.
239 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
241 if (tsk->thread.saved_esp0)
243 v86 = (struct vm86plus_struct __user *)regs.ecx;
244 tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
245 tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
246 (long)&info.regs32 - (long)&info.regs.VM86_REGS_PART2);
251 info.vm86plus.is_vm86pus = 1;
252 tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
253 do_sys_vm86(&info, tsk);
254 ret = 0; /* we never return here */
260 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
262 struct tss_struct *tss;
264 * make sure the vm86() system call doesn't try to do anything silly
266 info->regs.__null_ds = 0;
267 info->regs.__null_es = 0;
269 /* we are clearing fs,gs later just before "jmp resume_userspace",
270 * because starting with Linux 2.1.x they aren't no longer saved/restored
274 * The eflags register is also special: we cannot trust that the user
275 * has set it up safely, so this makes sure interrupt etc flags are
276 * inherited from protected mode.
278 VEFLAGS = info->regs.eflags;
279 info->regs.eflags &= SAFE_MASK;
280 info->regs.eflags |= info->regs32->eflags & ~SAFE_MASK;
281 info->regs.eflags |= VM_MASK;
283 switch (info->cpu_type) {
285 tsk->thread.v86mask = 0;
288 tsk->thread.v86mask = NT_MASK | IOPL_MASK;
291 tsk->thread.v86mask = AC_MASK | NT_MASK | IOPL_MASK;
294 tsk->thread.v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
299 * Save old state, set default return value (%eax) to 0
301 info->regs32->eax = 0;
302 tsk->thread.saved_esp0 = tsk->thread.esp0;
303 asm volatile("movl %%fs,%0":"=m" (tsk->thread.saved_fs));
304 asm volatile("movl %%gs,%0":"=m" (tsk->thread.saved_gs));
306 tss = init_tss + get_cpu();
307 tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0;
309 tsk->thread.sysenter_cs = 0;
310 load_virtual_esp0(tss, tsk);
313 tsk->thread.screen_bitmap = info->screen_bitmap;
314 if (info->flags & VM86_SCREEN_BITMAP)
315 mark_screen_rdonly(tsk);
316 __asm__ __volatile__(
317 "xorl %%eax,%%eax; movl %%eax,%%fs; movl %%eax,%%gs\n\t"
320 "jmp resume_userspace"
322 :"r" (&info->regs), "r" (tsk->thread_info) : "ax");
323 /* we never return here */
326 static inline void return_to_32bit(struct kernel_vm86_regs * regs16, int retval)
328 struct pt_regs * regs32;
330 regs32 = save_v86_state(regs16);
331 regs32->eax = retval;
332 __asm__ __volatile__("movl %0,%%esp\n\t"
334 "jmp resume_userspace"
335 : : "r" (regs32), "r" (current_thread_info()));
338 static inline void set_IF(struct kernel_vm86_regs * regs)
341 if (VEFLAGS & VIP_MASK)
342 return_to_32bit(regs, VM86_STI);
345 static inline void clear_IF(struct kernel_vm86_regs * regs)
347 VEFLAGS &= ~VIF_MASK;
350 static inline void clear_TF(struct kernel_vm86_regs * regs)
352 regs->eflags &= ~TF_MASK;
355 static inline void clear_AC(struct kernel_vm86_regs * regs)
357 regs->eflags &= ~AC_MASK;
360 /* It is correct to call set_IF(regs) from the set_vflags_*
361 * functions. However someone forgot to call clear_IF(regs)
362 * in the opposite case.
363 * After the command sequence CLI PUSHF STI POPF you should
364 * end up with interrups disabled, but you ended up with
365 * interrupts enabled.
366 * ( I was testing my own changes, but the only bug I
367 * could find was in a function I had not changed. )
371 static inline void set_vflags_long(unsigned long eflags, struct kernel_vm86_regs * regs)
373 set_flags(VEFLAGS, eflags, current->thread.v86mask);
374 set_flags(regs->eflags, eflags, SAFE_MASK);
375 if (eflags & IF_MASK)
381 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs * regs)
383 set_flags(VFLAGS, flags, current->thread.v86mask);
384 set_flags(regs->eflags, flags, SAFE_MASK);
391 static inline unsigned long get_vflags(struct kernel_vm86_regs * regs)
393 unsigned long flags = regs->eflags & RETURN_MASK;
395 if (VEFLAGS & VIF_MASK)
397 return flags | (VEFLAGS & current->thread.v86mask);
400 static inline int is_revectored(int nr, struct revectored_struct * bitmap)
402 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
404 :"m" (*bitmap),"r" (nr));
408 #define val_byte(val, n) (((__u8 *)&val)[n])
410 #define pushb(base, ptr, val, err_label) \
414 if (put_user(__val, base + ptr) < 0) \
418 #define pushw(base, ptr, val, err_label) \
422 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
425 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
429 #define pushl(base, ptr, val, err_label) \
433 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
436 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
439 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
442 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
446 #define popb(base, ptr, err_label) \
449 if (get_user(__res, base + ptr) < 0) \
455 #define popw(base, ptr, err_label) \
458 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
461 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
467 #define popl(base, ptr, err_label) \
470 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
473 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
476 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
479 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
485 /* There are so many possible reasons for this function to return
486 * VM86_INTx, so adding another doesn't bother me. We can expect
487 * userspace programs to be able to handle it. (Getting a problem
488 * in userspace is always better than an Oops anyway.) [KD]
490 static void do_int(struct kernel_vm86_regs *regs, int i,
491 unsigned char __user * ssp, unsigned short sp)
493 unsigned long __user *intr_ptr;
494 unsigned long segoffs;
496 if (regs->cs == BIOSSEG)
498 if (is_revectored(i, &KVM86->int_revectored))
500 if (i==0x21 && is_revectored(AH(regs),&KVM86->int21_revectored))
502 intr_ptr = (unsigned long __user *) (i << 2);
503 if (get_user(segoffs, intr_ptr))
505 if ((segoffs >> 16) == BIOSSEG)
507 pushw(ssp, sp, get_vflags(regs), cannot_handle);
508 pushw(ssp, sp, regs->cs, cannot_handle);
509 pushw(ssp, sp, IP(regs), cannot_handle);
510 regs->cs = segoffs >> 16;
512 IP(regs) = segoffs & 0xffff;
519 return_to_32bit(regs, VM86_INTx + (i << 8));
522 int handle_vm86_trap(struct kernel_vm86_regs * regs, long error_code, int trapno)
524 if (VMPI.is_vm86pus) {
525 if ( (trapno==3) || (trapno==1) )
526 return_to_32bit(regs, VM86_TRAP + (trapno << 8));
527 do_int(regs, trapno, (unsigned char __user *) (regs->ss << 4), SP(regs));
531 return 1; /* we let this handle by the calling routine */
532 if (current->ptrace & PT_PTRACED) {
534 spin_lock_irqsave(¤t->sighand->siglock, flags);
535 sigdelset(¤t->blocked, SIGTRAP);
537 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
539 send_sig(SIGTRAP, current, 1);
540 current->thread.trap_no = trapno;
541 current->thread.error_code = error_code;
545 void handle_vm86_fault(struct kernel_vm86_regs * regs, long error_code)
547 unsigned char opcode;
548 unsigned char __user *csp;
549 unsigned char __user *ssp;
550 unsigned short ip, sp;
551 int data32, pref_done;
553 #define CHECK_IF_IN_TRAP \
554 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
556 #define VM86_FAULT_RETURN do { \
557 if (VMPI.force_return_for_pic && (VEFLAGS & (IF_MASK | VIF_MASK))) \
558 return_to_32bit(regs, VM86_PICRETURN); \
561 csp = (unsigned char __user *) (regs->cs << 4);
562 ssp = (unsigned char __user *) (regs->ss << 4);
569 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
570 case 0x66: /* 32-bit data */ data32=1; break;
571 case 0x67: /* 32-bit address */ break;
572 case 0x2e: /* CS */ break;
573 case 0x3e: /* DS */ break;
574 case 0x26: /* ES */ break;
575 case 0x36: /* SS */ break;
576 case 0x65: /* GS */ break;
577 case 0x64: /* FS */ break;
578 case 0xf2: /* repnz */ break;
579 case 0xf3: /* rep */ break;
580 default: pref_done = 1;
582 } while (!pref_done);
589 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
592 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
601 unsigned long newflags;
603 newflags=popl(ssp, sp, simulate_sigsegv);
606 newflags = popw(ssp, sp, simulate_sigsegv);
612 set_vflags_long(newflags, regs);
614 set_vflags_short(newflags, regs);
621 int intno=popb(csp, ip, simulate_sigsegv);
623 if (VMPI.vm86dbg_active) {
624 if ( (1 << (intno &7)) & VMPI.vm86dbg_intxxtab[intno >> 3] )
625 return_to_32bit(regs, VM86_INTx + (intno << 8));
627 do_int(regs, intno, ssp, sp);
636 unsigned long newflags;
638 newip=popl(ssp, sp, simulate_sigsegv);
639 newcs=popl(ssp, sp, simulate_sigsegv);
640 newflags=popl(ssp, sp, simulate_sigsegv);
643 newip = popw(ssp, sp, simulate_sigsegv);
644 newcs = popw(ssp, sp, simulate_sigsegv);
645 newflags = popw(ssp, sp, simulate_sigsegv);
652 set_vflags_long(newflags, regs);
654 set_vflags_short(newflags, regs);
667 * Damn. This is incorrect: the 'sti' instruction should actually
668 * enable interrupts after the /next/ instruction. Not good.
670 * Probably needs some horsing around with the TF flag. Aiee..
678 return_to_32bit(regs, VM86_UNKNOWN);
684 /* FIXME: After a long discussion with Stas we finally
685 * agreed, that this is wrong. Here we should
686 * really send a SIGSEGV to the user program.
687 * But how do we create the correct context? We
688 * are inside a general protection fault handler
689 * and has just returned from a page fault handler.
690 * The correct context for the signal handler
691 * should be a mixture of the two, but how do we
692 * get the information? [KD]
694 return_to_32bit(regs, VM86_UNKNOWN);
697 /* ---------------- vm86 special IRQ passing stuff ----------------- */
699 #define VM86_IRQNAME "vm86irq"
701 static struct vm86_irqs {
702 struct task_struct *tsk;
706 static spinlock_t irqbits_lock = SPIN_LOCK_UNLOCKED;
709 #define ALLOWED_SIGS ( 1 /* 0 = don't send a signal */ \
710 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
713 static irqreturn_t irq_handler(int intno, void *dev_id, struct pt_regs * regs)
718 spin_lock_irqsave(&irqbits_lock, flags);
719 irq_bit = 1 << intno;
720 if ((irqbits & irq_bit) || ! vm86_irqs[intno].tsk)
723 if (vm86_irqs[intno].sig)
724 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
725 /* else user will poll for IRQs */
727 spin_unlock_irqrestore(&irqbits_lock, flags);
731 static inline void free_vm86_irq(int irqnumber)
735 free_irq(irqnumber,0);
736 vm86_irqs[irqnumber].tsk = 0;
738 spin_lock_irqsave(&irqbits_lock, flags);
739 irqbits &= ~(1 << irqnumber);
740 spin_unlock_irqrestore(&irqbits_lock, flags);
743 void release_x86_irqs(struct task_struct *task)
746 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
747 if (vm86_irqs[i].tsk == task)
751 static inline int get_and_reset_irq(int irqnumber)
756 if (invalid_vm86_irq(irqnumber)) return 0;
757 if (vm86_irqs[irqnumber].tsk != current) return 0;
758 spin_lock_irqsave(&irqbits_lock, flags);
759 bit = irqbits & (1 << irqnumber);
761 spin_unlock_irqrestore(&irqbits_lock, flags);
764 enable_irq(irqnumber);
769 static int do_vm86_irq_handling(int subfunction, int irqnumber)
772 switch (subfunction) {
773 case VM86_GET_AND_RESET_IRQ: {
774 return get_and_reset_irq(irqnumber);
776 case VM86_GET_IRQ_BITS: {
779 case VM86_REQUEST_IRQ: {
780 int sig = irqnumber >> 8;
781 int irq = irqnumber & 255;
782 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
783 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
784 if (invalid_vm86_irq(irq)) return -EPERM;
785 if (vm86_irqs[irq].tsk) return -EPERM;
786 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, 0);
788 vm86_irqs[irq].sig = sig;
789 vm86_irqs[irq].tsk = current;
792 case VM86_FREE_IRQ: {
793 if (invalid_vm86_irq(irqnumber)) return -EPERM;
794 if (!vm86_irqs[irqnumber].tsk) return 0;
795 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
796 free_vm86_irq(irqnumber);